Frequent Questions

Since EPA placed the Phase 1 HWC NESHAP standards only in the CAA regulations, should states remove their RCRA combustion requirements from their regulations?

No. Under RCRA section 3009, states may not implement requirements that are less stringent than the federal program. When we placed the Phase 1 HWC MACT standards in the federal CAA regulations, we did not remove the combustion requirements from the federal RCRA regulations. Instead, we revised the RCRA regulations such that they no longer apply once a facility demonstrates compliance with the Phase 1 HWC NESHAP, with some exceptions related to compliance with omnibus requirements and/or compliance with alternatives (i.e., the RCRA requirements during start-up, shutdown, and malfunction events and the particulate matter standard for incinerators feeding low levels of metals). Thus, while states may not remove their RCRA combustion requirements from their regulations, they may revise their regulations as we have done in the federal program. We strongly encouraged this in the preamble to the final Phase I HWC NESHAP rule. By deferring the RCRA requirements (i.e. allowing the CAA requirements to supplant them), we believe that unnecessary duplication is eliminated between the RCRA and CAA regulatory programs.

It is important to note that the Phase 1 HWC NESHAP and our deferral of the RCRA requirements apply only to hazardous waste-burning incinerators, cement kilns, and lightweight aggregate kilns. Other source categories, such as hazardous waste-burning boilers and hydrochloric acid production furnaces, were not addressed in this NESHAP. They continue to be regulated under the RCRA combustion regulations. While we do plan to issue MACT standards for these hazardous waste combustors in the future, we have not done so yet. When we do, we will determine if the federal RCRA combustion requirements in total should be deferred to the CAA regulations and, if so, will encourage the authorized states to do likewise.

States are not obligated to follow our deferral recommendation. Authorized states are only required to modify their programs when EPA issues federal standards that are broader or more stringent than the existing federal standards. The revisions we made to the federal RCRA regulations through the Phase 1 HWC NESHAP, however, resulted in some RCRA requirements becoming less stringent. This is because we deferred the emissions requirements to another federal program. Although we strongly encourage authorized state RCRA programs to make a similar deferral, they are under no obligation to do so.